JEE Main & Advanced Mathematics Binomial Theorem and Mathematical Induction Question Bank Multinomial theorem, Terms free from radical sign in the expansion(a1/p+b1/q), Problems regarding to three four consecutive terms or coefficients

  • question_answer
    The number of integral terms in the expansion of \[{{\left( \sqrt{3}+\sqrt[8]{5} \right)}^{256}}\] is [AIEEE 2003]

    A) 32

    B) 33

    C) 34

    D) 35

    Correct Answer: B

    Solution :

    \[{{T}_{r+1}}={}^{256}{{C}_{r}}{{(\sqrt{3})}^{256-r}}{{(\sqrt[8]{5})}^{r}}\] \[={}^{256}{{C}_{r}}{{(3)}^{\frac{256-r}{2}}}{{(5)}^{r/8}}\] Terms would be integral if \[\frac{256-r}{2}\] and \[\frac{r}{8}\] both are positive integer. As 0 £ r £ 256, \[\therefore r=0,\,8,\,16,\,24,.....,256\] For above values of r, \[\left( \frac{256-r}{2} \right)\] is also an integer.


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